1. Field of Invention
The present invention relates to an optoelectronic chip packaging technology. More particularly, the present invention relates to a multi-chip build-up package of an optoelectronic chip.
2. Description of Related Art
Optoelectronic chips have been applied in video electronic products to provide various functions such as image sensing, image displaying, illuminating, optical storage, optical output, or optical input. As the optoelectronic chips usually have a large package size, the assembly space for the video electronic products is occupied and the electrical transmission path is quite long, thus a cross-talk effect easily occurs.
Referring to FIG. 1, an optoelectronic chip package 100 of an image sensor is in the form of single chip package and mainly includes a substrate 110, an optoelectronic chip 120, a plurality of bonding wires 130, and a transparent plate 140. The substrate 110 has an upper surface 111, a lower surface 112, and a wiring structure (not shown) electrically conducting the upper surface 111 and the lower surface 112. The substrate 110 usually is a multi-layer printed circuit board. An annular wall 113 is formed with the upper surface 111 of the substrate 110, so that the substrate 110 and the annular wall 113 form a chip accommodating cavity 114. The optoelectronic chip 120 is an image sensing chip, and is disposed on the upper surface 111 of the substrate 110 by means of adhering and is located in the chip accommodating cavity 114. A sensing region 121 and a plurality of bonding pads 122 are formed on the active surface of the optoelectronic chip 120. The bonding wires 130 are formed in the chip accommodating cavity 114 by means of wiring process, and are electrically connected to the bonding pads 122 of the optoelectronic chip 120 and the substrate 110. The transparent plate 140 is disposed on the annular wall 113, so as to seal the optoelectronic chip 120 and the bonding wires 130. In the above optoelectronic chip package 100, the optoelectronic chip 120 is electrically conducted to a digital signal processor chip (not shown) on an external circuit board via the bonding wires 130 and the substrate 110, and the transmission path is relatively long, so that the image cannot be quickly processed and thus the cross-talk effect easily occurs.
Taiwan patent No. M246808 entitled “Build-up Structure for Image Sensor” has disclosed an image sensor package including a wiring build-up structure. An image sensing chip is accommodated in a chip cavity of a substrate, and the image sensing chip has a sensing region facing upward. The wiring build-up structure is formed on the image sensing chip of the substrate. As the wiring build-up structure is formed on the active surface of the image sensing chip and the substrate, the sensing region of the image sensing chip may be easily contaminated in the build-up package process. The wiring build-up structure must have a window which cannot shield the sensing region. Thus, the conductive wiring arranged in the wiring build-up structure is limited and cannot become compact. Moreover, it is required to reserve a window in the wiring build-up structure, so that the manufacturing cost is increased.